Buchmann



June 5, 1956 A. BUCHMANN 2,749,458

SAFETY APPARATUS FOR MAGNETOS Filed June 3, 1955 INVENTOR. H\ bmBuahmann F/G. 4 BY:

SAFETY ArrAnArus FUR MAGNETOS Albin Buchmann, Soienre, Switzerland,assignor to Scintilla Ltd, Soleure, Switzerland The present inventionrelates to magnetos. More particularly, the present invention relates toa safety apparatus for use with magnetos to prevent coils thereof fromburning out.

One of the objects of the present invention is to provide an apparatusfor automatically short circuiting a magneto coil when the speed ofrotation of the magneto reaches a predetermined value.

Another object of the present invention is to provide a short circuitingapparatus of this type with a means for manually setting the same in anoperating position.

A further object of the present invention is to provide a shortcircuiting apparatus of this type with a means for manually operatingthe short circuiting apparatus at will.

An additional object of the present invention is to provide a shortcircuiting apparatus of the above type which short circuits a coil whosecircuit is closed and opened by an interrupter irrespective of theposition of this interrupter.

With the above objects in view, the present invention mainly consists ofa magneto having a primary coil and a housing in which a distributor armof the magneto is turnably mounted. A centrifugal regulator or controlmeans is provided to automatically ground the distributor arm when thespeed of rotation thereof reaches a predetermined value, this controlmeans being connected to the arm for rotation therewith and beingturnable by centrifugal force to and from a grounding position where thedistributor arm is grounded by the control means. A short circuit meansis mounted on the housing for short circuiting the primary coil of themagneto, this short circuiting means having an actuating member foractuating the same, and this actuating member being located in the pathof movement of the centrifugal control means when the latter is in itsgrounding position to be engaged and moved by the control means foractuating the short circuiting means.

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following description of specificembodiments when read in connection with the accompanying drawings, inwhich:

Fig. l is a fragmentary, partly sectional and partly diagrammaticelevational view of a magneto constructed in accordance with the presentinvention;

Fig. 2 is a fragmentary, partly sectional view taken along line 2-2 ofFig. 1 in the direction of the arrows;

Fig. 3 is a fragmentary illustration of the structure of Fig. 2 in theshort circuiting position thereof;

Fig. 4 is a fragmentary partly sectional view taken along line 4-4 ofFig. 1 in the direction of the arrows; and

2,749,458 Patented June 5, 1956 of the magneto and an interrupter andshort circuiting means associated therewith.

Referring now to the drawings, Fig. 1 shows a housing 1 adapted to bemounted in a vertical position on an internal combustion engine or thelike, this housing 1 of the magneto being electrically conductive so asto ground parts of the magneto, as described below. A rotor shaft 2 isturnably mounted on the housing 1 and is adapted to be rotated in aknown way from the crank shaft of the internal combusion engine. A cam 3is connected to the shaft 2 for rotation therewith and forms a part ofan interrupter for opening and closing an interrupter switch of theprimary coil of the magneto. A carrier 4 of electrical insulatingmaterial also is connected to the shaft 2 for rotation therewith andcarries an electrically conductive distributor arm 5 from which currentjumps in a known way to the several electrodes 10 located in distributorhead 11 during rotation of carrier 4 and arm 5 so as to cause fuel-airmixtures in the cylinders of the engine to be ignited in a predeterminedsequence, as is Well known.

A support 12 is grounded to the housing 1 through the cam 3 and carriesan electrically conductive pivot pin 7 on which a centrifugal regulatoror control member 6 is turnably mounted, this support 12 being locatedbetween members 3 and 4 and connected to the former for rotationtherewith during rotation of shaft 2. The centrifugal control member 6is a centrifugal control means for limiting the speed of rotation of theengine, this control member 6 being electrically conductive and groundedthrough members 7, 12, 3, and 1. The control member 6 includes a pair ofbell cranks formed by a pair of long stirrup-formed arms 6' and a pairof shorter arms 6" respectively joined to arms 6', the arms 6" carryingbetween themselves a weight 8 and a spring 9 being connected to theweight 3 and a part of support 12 spaced from pivot pin 7 (Fig. 4) tourge the control member 6 to the solid line position shown in Fig. 1. Apart of the front arm 6" of Fig. 1 is broken away to show the spring 9and weight 8.

As the speed of rotation of the engine increases, the speed of rotationof shaft 2 also increases, as is Well known, and by centrifugal forcethe weight 8 and the control member 6 turn against the action of spring9 in a clockwise direction about pin 7, as viewed in Fig. 1, so that thecontrol member 6 becomes located in the dotted line position shown inFig. 1 where the free end of the control member joining arms 6' closelyapproaches the arm 5 to cause current to jump from the latter to thecontrol member 6 to be grounded thereby so as to stop operation of theengine and thereby limit the speed of rotation thereof. The controlmember 6 includes at its right hand side, as viewed in Fig. 1, ahorizontal extension Fig. 5 is a. fragmentary wiring diagram showing acoil extending between arms 6 and provided with a downwardly extendinglug 6" for a purpose to be described below.

The wall portion of the housing 1 is formed with an opening passingtherethrough, as is shown at the lower right hand side of Fig. 1, and anelectrically conductive member 13 is provided with a tubular bearingportion extending through this opening and having an outer threadedsurface located at the exterior of housing 1 and engaged by a nut 14 onthe outside of housing 1 for fixing member 13 thereon, as is shown inFig. 1. As is apparent from Fig. 2, the member 13 is formed in theinterior of housing 1 with a notch in which an electrically conductiveswitch member 16 is located, this switch member forming almost acomplete circle and being fixed to a shaft 15 which extends through thetubular bearing portion of member 13 to be turnably carried there by, ahandle 17 of electrical insulating material being fixed to the shaft 15on the outside of housing 1. Shaft 15 may be made of electricalinsulating material, if dcsired. A switch operating member 18 is fixedto the switch member 16 and extends upwardly therefrom as shown in Fig.2. In the interior of housing 1, the member 13 is formed with a recessin which a block 19 of electrical insulating material is located, thisblock 19 carrying a springy switch member 2t? which is connected by thelead 21 to the primary coil 22 of the magneto (Fig. and the free end ofswitch member 24) hearing against an insulated part 13' of member 13,when the parts are in the positions shown in Fig. 2.

Fig. 5 diagrammatically shows the primary coil 22 of the magneto and theinterrupter switch 23 electrically connected thereto for opening andclosing the circuit thereof, this switch 23 being engaged by theinterrupter cam 3 which opens the switch 23 a ainst the action of spring24. As is shown in Fig. 5, the lead 21 is connected to the primary coil2?. and the sv'itch member 29 for short circuiting the primary coil 22when switch member 2i) is grounded by contact with member 16. As isapparent from Fig. 5, interrupter 23 is bridged by line zll and. switch16, 20 so that when this latter switch is closed the coil 22 will beshort circuited irrespective of the position of the interrupter.

The above-described apparatus operates as follows:

As the speed of rotation of the engine increases, the arms 6" approacharm 5 to eventually ground the latter when the speed of rotation of theengine and arm 5 reaches a predetermined value, as was described above.The turning of the centrifugal control member 6 causes the lug 6' tobecome lowered until it is located at the elevation of switch operatingmember 18, as shown in dotdash lines in Fig. 2, and at this time, whenthe regulator 6 is in its grounding position for grounding arm 5, theturning lug 6", which moves in the direction of the arrow shown at thetop of Fig. 2, will engage switch operating member 18 to turn the latterand switch member 16, shaft and handle 17 therewith to the positionshown Fig. 3 where the switch operating member 18 engages an inclinedface of member 13. in this position, switch member 16 engages switchmember 2b to close the switch 16, 20, and the lead 21 connected to theprimary coil 22 is grounded through the switch members and 16, member 13and housing ll, so that the primary coil 22 cannot become burnt out. Thegrounding of arm 5 by the control member 6 short circuits the secondarycoil of the magnetosince one end of the secondary coil is alreadygrounded. The effective result is a Zero load to the primary coil and anincreased current flow through the primary coil will take place whichmight cause the primarycoil to be burned out if it were notautomatically short circuited by the apparatus of the invention.

To reset the apparatus it is only necessary to turn the handle 17 so asto rotate shaft 15 and switch member 16 therewith to again locate theparts in the position shown Fig. It should be noted that the handle 17not only serves to reset the apparatus. This handle also may be used toshort circuit the primary coil 22 at will so that the engine may bestopped at any time in this way.

I It will be understood that each of the elements described above, ortwo or more together, may also find a useful application in other typesof ma netos differing from the types described above.

While the invention has been illustrated and described as embodied insafety apparatus for magnetos, it is not intended to be limited to thedetails shown, since various modifications and structural changes may bemade without departing in any way from the spirit of the presentinvention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can by applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. In a magneto having a primary coil, in combination, a housing; adistributor arm turnably mounted in said housing; centrifugal controlmeans for automatically grounding said distributor arm when the speed ofrotation thereof reaches a predetermined value; and short circuitingmeans mounted on said housing for short circuiting the primary coil ofthe magneto, said short circuiting means being located adjacent saidcentrifugal control means to be actuated thereby for short circuitingthe primary coil when said control means grounds said distributor arm.

2. In a magneto having a primary coil, in combination, a housing; adistributor arm turnably mounted in said housing; centrifugal controlmeans for automatically grounding said distributor arm when the speed ofrotation thereof reaches a predetermined value, said control means beingconnected to said arm for rotation therewith and being turnable bycentrifugal force to and from a grounding position where said arm isgrounded by said control means; and short circuiting means mounted onsaid housing for short circuiting the primary coil of the magneto, saidshort circuiting means having an actuating member for actuating the sameand said actuating member being located in the path of movement of saidcentrifugal control means when the latter is in said grounding positionthereof to be engaged and moved by said control means for actuating saidshort circuiting means.

I 3. In a magneto having a primary coil, in combination, a housing; adistributor arm turnably mounted in said housing; centrifugal controlmeans for automatically grounding said distributor arm when the speed ofrotation thereof reaches a predetermined value, said control means beingconnected to said arm for rotation therewith and being turnable bycentrifugal force to and from a grounding position where said arm isgrounded by said control means; short circuiting means mounted on saidhousing for short circuiting the primary coil of the magneto, said shortcircuiting means having an actuating member for actuating the same andsaid actuating member being located in the path of movement of saidcentrifugal control means when the latter is in said grounding positionthereof to be engaged and moved by said control means for actuating saidshort circuiting means; and manually operable setting means operativelyconnected to said short circuiting means for setting the latter in aposition Where the primary coil is not short circuited.

4. In a magneto having a primary coil, in combination, a housing; adistributor arm turnably mounted in said housing; centrifugal controlmeans for automatically grounding said distributor arm when the speed ofrotation thereof reaches a predetermined value, said control means beingconnected to said arm for rotation therewith and being turnable bycentrifugal force an and from a'grounding position where said arm isgrounded by said control means; and switch means adapted to be connectedto the primary coil of the magneto for short circuiting the same whensaid switch means is in the closed position thereof, said switch meanshaving a switch operating member located in the path of movement of saidcentrifugal control means when the latter is in said grounding positionthereof to be engaged and moved by said control means to close saidswitch means for short circuiting the primary coil.

5. In a magneto having a primary coil, in combination, a housing; adistributor arm turnably mounted in said housing; centrifugal controlmeans for automatically 7 grounding said distributor arm when the speedof rotation thereof reaches a predetermined value, said control meansbeingeonnected to said arm for rotation therewith and being turnable bycentrifugal force to and from a grounding position where said arm isgrounded by said control means; switch means adapted to be connected tothe primary coil of the magneto for short circuiting the same when saidswitch means is in the closed position thereof, said switch means havinga switch operating member located in the path of movement of saidcentrifugal control means when the latter is in said grounding positionthereof to be engaged and moved by said control means to close saidswitch means for short circuiting the primary coil; and manuallyoperable means operatively connected to said switch means for settingthe same in the open position thereof.

6. In a magneto, in combination, a primary coil; an electricallyconductive housing for grounding parts of the magneto; a distributor arminsulated from said housing and being turnably mounted therein; anelectrically conductive centrifugal control member insulated from saidarm and being connected thereto for rotation therewith, said controlmember being electrically connected to said housing and being turnableto and from a grounding position adjacent said arm for grounding thelatter when the speed of rotation of said arm reaches a predeterminedvalue; and a short circuiting switch connected to said primary coil forshort circuiting the latter when said switch is closed, said switchincluding a switch member carried by said housing and being electricallyconnected thereto for grounding the primary coil when said switch isclosed, and a switch operating member connected to said switch memberand located in the path of movement of said control member when thelatter is in said grounding position thereof to be engaged and moved bysaid control member for closing said switch to short circuit saidprimary coil.

7. In a magneto, in combination, a primary coil; an electricallyconductive housing for grounding parts of the magneto; a distributor arminsulated from said housing and being turnably mounted therein; anelectrically conductive centrifugal control member insulated from saidarm and being connected thereto for rotation therewith, said controlmember being electrically connected to said housing and being turnableto and from a grounding position adjacent said arm for grounding thelatter when the speed of rotation of said arm reaches a predeterminedvalue; an interrupter electrically connected to the primary coil foropening and closing the circuit thereof; and a short circuiting switchbridging said interrupter and being electrically connected to saidprimary coil for short circuiting the latter irrespective of theposition of said interrupter, when said switch is closed, said switchincluding a switch member carried by said housing and being electricallyconnected thereto for grounding the primary coil when said switch isclosed, and a switch operating member connected to said switch memberand located in the path of movement of said control member when thelatter is in said grounding position thereof to be engaged and moved bysaid control member for closing said switch to short circuit saidprimary coil.

8. In a magneto, in combination, a primary coil; an electricallyconductive housing for grounding parts of the magneto, said housinghaving a wall portion formed with an opening passing therethrough; adistributor arm insulated from said housing and being turnably mountedtherein; an electrically conductive centrifugal control member insulatedfrom said arm and being connected thereto for rotation therewith, saidcontrol member being electrically connected to said housing and beingturnable to and from a grounding position adjacent said arm forgrounding the latter when the speed of rotation of said arm reaches apredetermined value; an electrically conductive tubular bearing memberfixed to said housing and extending through said opening thereof; afirst switch member insulated from said bearing member and being carriedthereby in the interior of said housing, said first switch member beingelectrically connected to the primary coil; a shaft extending throughsaid tubular hearing member and being turnably supported thereby; and asecond switch member electrically connected to said bearing member to begrounded by contact between the latter and said housing, said secondswitch member being located opposite said first switch member and beingfixed to said shaft for turning movement therewith to and from aposition engaging said first switch member for grounding the primarycoil; and a switch operating member fixed to said second switch memberand being located in the path of movement of said control member whenthe latter is in said grounding position thereof to be engaged and movedthereby for turning said second switch member and said shaft therewithto a position where said second switch member engages said first switchmember.

9. In a magneto, in combination, a primary coil; an electricallyconductive housing for grounding parts of the magneto, said housinghaving a wall portion formed with an opening passing therethrough; adistributor arm insulated from said housing and being turnably mountedtherein; an electrically conductive centrifugal control member insulatedfrom said arm and being connected thereto for rotation therewith, saidcontrol member being electrically connected to said housing and beingturnable to and from a grounding position adjacent said arm forgrounding the latter When the speed of rotation of said arm reaches apredetermined value; an electrically conductive tubular bearing memberfixed to said housing and extending through said opening thereof; afirst switch member insulated from said bearing member and being carriedthereby in the interior of said housing, said first switch member beingelectrically connected to the primary coil; a shaft extending throughsaid tubular bearing member and being turnably supported thereby; and asecond switch member electrically connected to said bearing member to begrounded by contact between the latter and said housing, said secondswitch member being located opposite said first switch member and beingfixed to said shaft for turning movement therewith to and from aposition engaging said first switch member for grounding the primarycoil; a switch operating member fixed to said second switch member andbeing located in the path of movement of said control member when thelatter is in said grounding position thereof to be engaged and movedthereby for turning said second switch member and said shaft therewithto a position where said second switch member engages said first switchmember; and a handle located outside of said housing and being fixed tosaid shaft for turning the latter so that the primary coil may begrounded at will by turning said handle and so that said second switchmember may be manually turned away from said first switch member by saidhandle.

10. In a magneto, in combination, a primary coil; an electricallyconductive housing for grounding parts of the magneto, said housinghaving a wall portion formed with an opening passing therethrough; adistributor arm insulated from said housing and being turnably mountedtherein; an electrically conductive centrifugal control member insulatedfrom said arm and being connected thereto for rotation therewith, saidcontrol member being electrically connected to said housing and beingturnable to and from a grounding position adjacent said arm forgrounding the latter when the speed of rotation of said arm reaches apredetermined value; an electrically conductive tubular bearing memberfixed to said housing and extending through said opening thereof; afirst switch member insulated from said bearing member and being carriedthereby in the interior of said housing, said first switch member beingelectrically connected to the primary coil; a shaft extending throughsaid tubular bearing member and being turnably supported thereby; and asecond switch member electrically connected to said bearing member to begrounded by contact between the latter 7 ri'r'l-sziid housihg'; s'fiid'Second switch member being 10'- eated ofiposite said first switch memberand being fixed to said shift for t'u'rnihg movement therewith to andfr'crn '2' position engaging said first switch member for grounding theprimary coil; a switch ope'ra'ting member fixed to said second switchmember and being located in the path of ifioveinent of 'saidcontrolmember when he latter' is in said grounding position thereof to beengaged'and moved thereby for turning said second switch member and saidshaft therewith to a position where said second switch member engagessaid first switch member; and a handle located outside of said housingafid being fixed to said 'shziftfor fiirning the latter so ReferencesCited in the file of this patent UNITED STATES PATENTS 1,319,256 VanDeventer Oct. 21 1919 1,502,594 Spiv a July 22, 19 24 1,925,883 SmithSept. 5, 1933 2,324,169 Moran July 13, 1943

